2019 Fiscal Year Final Research Report

An observational study on the large-scale environments that determine precipitation characteristics over tropical and midlatitude oceans

Research Project

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Project/Area Number	19K21050
Project/Area Number (Other)	18H05869 (2018)
Research Category	Grant-in-Aid for Research Activity Start-up
Allocation Type	Multi-year Fund (2019) Single-year Grants (2018)
Review Section	0204:Astronomy, earth and planetary science, and related fields
Research Institution	The University of Tokyo
Principal Investigator	Yokoyama Chie 東京大学, 大気海洋研究所, 特任助教 (80649236)
Project Period (FY)	2018-08-24 – 2020-03-31
Keywords	降水特性 / 豪雨 / 衛星観測 / 将来変化 / GPM衛星 / 降水の組織化 / 梅雨
Outline of Final Research Achievements	The method to estimate changes in precipitation characteristics with those in large-scale environments was applied to precipitation over global oceans. Based on the knowledge obtained through both statistical and case studies, we identified three types of rainfall events (REs) over global oceans to quantify their dependencies on large-scale vertical velocity in the mid-troposphere and sea surface temperature. Using these precipitation-environment relationships, we reconstructed precipitation distributions of each type of RE over global oceans with large-scale environments. Seasonal mean distributions of the reconstructed precipitation were shown to be well correlated with observation in a manner consistent with previous studies. While the estimation of changes in reconstructed precipitation was shown to be useful over global oceans to some degree, further validation was found to be needed for the reconstructed precipitation especially over tropical oceans.
Free Research Field	気象学
Academic Significance and Societal Importance of the Research Achievements	衛星観測から全球海上の降水特性と大規模場との関係を調査した。豪雨事例の解析や統計解析を通して組織化システムの発生・維持の仕組みの理解を深めた。また、衛星による降水の立体構造の統計が比較的少ない中緯度に対し、卓越する雨域特性及び指標となる大規模場に関する統計的知見を得た。更に、全球海上で同定された3タイプの雨域について、季節・領域間でロバストな大規模場依存性を見出した。これらの関係を用い大規模場からタイプ別降水分布を再構築し、現実大気において大規模場変化から全球の降水特性変化を推定する手法の有効性及び今後の課題を示した。研究成果は、全球海上の降水特性の将来変化を推定するための研究に役立つ。